// @file stringencoding.cpp Represents and defines string-encoded plaintext
// objects in Palisade.
// @author TPOC: contact@palisade-crypto.org
//
// @copyright Copyright (c) 2019, New Jersey Institute of Technology (NJIT)
// All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
// 1. Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution. THIS SOFTWARE IS
// PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
// EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
// INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include "encoding/stringencoding.h"

namespace lbcrypto {

static const size_t charPtm = (1 << 8);
static const uint32_t CHARMARKER = (1 << 7);

bool StringEncoding::Encode() {
  if (this->isEncoded) return true;
  auto mod = this->encodingParams->GetPlaintextModulus();

  if (mod != 256) {
    PALISADE_THROW(config_error, "Plaintext modulus must be " +
                                     std::to_string(charPtm) +
                                     " for string encoding");
  }

  if (this->typeFlag == IsNativePoly) {
    this->encodedNativeVector.SetValuesToZero();
    size_t i = 0;
    for (; i < ptx.size() && i < this->encodedNativeVector.GetLength(); i++) {
      this->encodedNativeVector[i] = ptx[i];
    }
    for (; i < this->encodedNativeVector.GetLength(); i++) {
      this->encodedNativeVector[i] = CHARMARKER;
    }
  } else {
    this->encodedVector.SetValuesToZero();
    size_t i = 0;
    for (; i < ptx.size() && i < this->encodedVector.GetLength(); i++) {
      this->encodedVector[i] = ptx[i];
    }
    for (; i < this->encodedVector.GetLength(); i++) {
      this->encodedVector[i] = CHARMARKER;
    }
  }

  if (this->typeFlag == IsDCRTPoly) {
    this->encodedVectorDCRT = this->encodedVector;
  }

  this->isEncoded = true;
  return true;
}

template <typename P>
static void fillPlaintext(const P& poly, string& str,
                          const PlaintextModulus& mod) {
  str.clear();
  for (size_t i = 0; i < poly.GetLength(); i++) {
    uint32_t ch = (poly[i].ConvertToInt() % mod) & 0xff;
    if (ch == CHARMARKER) break;
    str += static_cast<char>(ch);
  }
}

bool StringEncoding::Decode() {
  auto mod = this->encodingParams->GetPlaintextModulus();

  if (this->typeFlag == IsNativePoly)
    fillPlaintext(this->encodedNativeVector, this->ptx, mod);
  else
    fillPlaintext(this->encodedVector, this->ptx, mod);

  return true;
}

} /* namespace lbcrypto */
